import java.util.Scanner;
//不太会做。。
public class Main{
    
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            System.out.println(run(n));
        }
    }
    
    public static int run(int x){
        if(x > 2){
            int row = 2*x - 1;
            int[][] arr = new int[x][row];
            //遍历行赋值
            for(int j = 0; j < x; j++){
                //遍历列赋值
                for(int i = 0; i < row; i++){
                    if(j == 0){
                        if(i == x -1){
                            arr[j][i] = 1;
                        }else{
                            arr[j][i] = 0;
                        }
                    }else{
                        if(i == 0){
                            arr[j][i] = arr[j-1][i] + arr[j-1][i+1];
                        }else if(i == row - 1){
                            arr[j][i] = arr[j-1][i-1] + arr[j-1][i];
                        }else{
                            arr[j][i] = arr[j-1][i-1] + arr[j-1][i] + arr[j-1][i+1];
                        }
                    }
                }
            }
            
            //遍历处第一个偶数
            for(int i = 0; i < row; i++){
                if(arr[x-1][i]%2 == 0){
                    return i+1;
                }
            }
        }
        return -1;
    }
}